From Wikipedia, the free encyclopedia

Sclerosponges are sponges with a soft body
that covers a hard, often massive skeleton made of calcium
carbonate, either aragonite or calcite. Because of their long life span
(500-1,000 years) it is thought that analysis of the aragoniteskeletons of these sponges
could extend data regarding oceantemperature, salinity, and other variables farther into the
past than has been previously possible. Their dense skeletons are
deposited in an organized chronological manner, in concentric
layers or bands. The layered skeletons look similar to reefcorals. Therefore sclerosponges are also called
coralline sponges.

Sclerosponges were first proposed as a class of sponges,
Sclerospongiae, in 1970 by Hartman and Goreau.[1]
However, it was later found by Vacelet that sclerosponges occur in
different classes of Porifera.[2] That
means that sclerosponges are not a closely related (taxonomic) group of sponges.
Like bats and birds that independently developed the ability to
fly, different sponges developed the ability to build a calcareous
skeleton independently and during different times in Earth history. Fossil sclerosponges are
already known from the Cambrian
period.[3]

Sclerosponges include the species Ceratoporella
nicholsoni, Stromatospongia vermicola,
Hispidopetra miniana, S. norae, Goreauiella
auriculatra, and Merlia sp., which were described in
detail by Lang et al. in 1975.[4]